1. Field of the Invention
Example embodiments relate to a voltage select circuit and an integrated circuit.
2. Related Art
A semiconductor memory device typically has both Random Access Memory (RAM) in and from which data can be freely written and erased and Read Only Memory (ROM) which can retain data even without supply of power, and thus ROM has recently being widely adopted as the storage media of portable electronic devices, such as mobile phone, digital cameras, Personal Digital Assistants (PDAs), and MP3 players.
Memory cells of a semiconductor memory device are coupled to word lines and bit lines, and a particular memory cell is selected by selecting a word line and a bit line.
A program operation is performed on a page basis. Memory cells coupled to one word line correspond to at least one page. In order to perform a program operation, a program voltage is supplied to a word line selected for a program, and a pass voltage is supplied to the remaining word lines.
Here, the program voltage or the pass voltage is supplied to each word line via a global word line. Furthermore, the global word lines are coupled to a voltage supply unit of a non-volatile memory device and are supplied with voltages necessary for program and other operations.
The voltages supplied to the global word lines are determined in response to a control signal inputted to a control unit for controlling operation of the semiconductor memory device. That is, in response to the control signal, a program voltage is supplied to a global word line coupled to a selected word line and the pass voltage is supplied to global word lines coupled to the remaining word lines. To this end, the control unit performs control functions so that a circuit for generating various voltages can generate the various voltages, and the generated voltages can be supplied to the global word lines.
Meanwhile, in the program operation of the semiconductor memory device, a local self-boosting method of supplying voltage is used in the program operation, in various levels, in order to prevent threshold voltages of memory cells unselected for a program from being shifted.
If types of the voltages supplied to the global word lines are diversified, the number of control signals generated from the control unit in order to set the types of the voltages necessary for the respective global word lines is also increased. Furthermore, the area of the circuits of the semiconductor memory device may be increased because the number of circuits for selecting one of the voltages is increased.